1. Field of the Invention
This invention relates to tornado alarm systems and particularly to tornado alarm systems that monitor three weather parameters.
2. Description of Related Art
Tornadoes are some of the most devastating of all weather phenomena. Part of the significance of their power is that they are relatively unpredictable. Although forecasters can monitor conditions for a wide area, there is no simple way to pinpoint where a tornado may hit. Once on the ground, a tornado is easy to monitor, but by then, it is often too late for victims in its path. If a tornado hits during waking hours, it is much more likely that people's lives may be saved. Warnings can be broadcast over the affected area and people will most likely hear them. It is at night, when people are sleeping that there is the most danger.
To help in these efforts, tornado alarms have been invented. Although these devices may prove useful, they are not as effective as they could be. Many devices monitor a single parameter associated with tornadoes. For example, U.S. Pat. Nos. 5,612,667, 3,631,435, 3,646,540, and 4,632,052, all use barometric pressure to alert the user to the presence of a tornado. It is well known that a sudden drop in barometric pressure occurs just before a tornado strike. Unfortunately, the drop occurs at the time of inception of the tornado. In other words, when the tornado is already there. Thus, these devices do not give enough time for an adequate warning. Moreover, by focusing only on the barometric pressure, there are likely to be times when the alarm does not really indicate a tornado. Such false alarms reduce the usefulness of these devices.
U.S. Pat. No. 4,812,825 uses a superhetrodyne receiver to detect electromagnetic energy produced by a tornado. This device, like the others above, only measures one parameter associated with tornadoes, produces an alarm only when the tornado is very close, and is subject to confusion from other radio signals and noise.
U.S. Pat. Nos. 5,379,025 and 5,801,636 measure seismic waves generated by tornadoes. As before, the problem with these devices is that they only measure one parameter, it is a parameter that only exists when a tornado is very close, and it is subject to confusion and false signals due to other causes of seismic activity.
U.S. Pat. No. 5,867,805 takes a different approach. This patent uses a small computer that monitors all of the essential weather data, temperature, static electricity, humidity, barometric pressure, and others. It is also linked to an emergency broadcasting radio station. This device remains silent until and emergency signal is broadcast. The device then begins to monitor local weather conditions (if one chooses that mode). These data are then compared to a stored database of weather conditions for several years. When the conditions match a previous dangerous condition, the computer alerts the user to the danger. Although this device is less subject to false alarms, it first requires an emergency broadcast signal and then it must find a similar weather pattern in the database before it will alert the user. If there is no signal or if the perceived pattern is not stored; there is no warning.